Giant Frugivorous Monitor Lizards in the Philippines

Giant Frugivorous Monitor Lizards in the Philippines
Daniel Bennett. Leeds University, UK ([email protected])
Report on work sponsored by the BP Conservation Programme
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PROJECT SUMMARY ...........................................................................................4
PROJECT BACKGROUND ...................................................................................5
SURVEYS ACROSS THE PHILIPPINES...................................................................................................... 6
Summary ........................................................................................................................................................... 6
Background ....................................................................................................................................................... 7
Panay ................................................................................................................................................................. 8
Camiguin Norte ................................................................................................................................................ 8
Alabat ................................................................................................................................................................ 8
Mount Makiling, Luzon ................................................................................................................................... 9
Rizal Province, Luzon ...................................................................................................................................... 9
Sierra Madre, Luzon......................................................................................................................................... 9
RESEARCH ON POLILLO ..................................................................................11
Study site......................................................................................................................................................... 11
STUDY TECHNIQUES FOR GFLS......................................................................12
Summary ......................................................................................................................................................... 12
Background ..................................................................................................................................................... 13
Capture of Individuals .................................................................................................................................... 14
The Importance of Non-Intrusive Methodologies ........................................................................................ 14
Feces..................................................................................................................................................................... 15
Summary ......................................................................................................................................................... 15
Background ..................................................................................................................................................... 15
Methods ........................................................................................................................................................... 15
Results ............................................................................................................................................................. 16
Camera and Video Camera Traps and Direct Observation ....................................................................... 21
Background ..................................................................................................................................................... 21
Equipment and Methodology......................................................................................................................... 21
Results ............................................................................................................................................................. 24
Education, Training and Development .......................................................................................................... 28
CONCLUSIONS ...................................................................................................30
Effects of fragmentation and degradation ..................................................................................................... 30
Hunting............................................................................................................................................................ 32
FUTURE WORK ...................................................................................................33
Developing a Diet for Captive Animals ........................................................................................................ 33
Molecular Studies of Feces ............................................................................................................................ 34
On Polillo ........................................................................................................................................................ 35
In Sierra Madre ............................................................................................................................................... 35
Elsewhere ........................................................................................................................................................ 35
Team Members 2005-2006 ............................................................................................................................... 36
Thanks ................................................................................................................................................................. 36
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Financial Account.............................................................................................................................................. 37
REFERENCES .....................................................................................................38
APPENDICES ......................................................................................................40
Notes on Sibalom Natural Park Survey, Antique, Panay............................................................................. 41
Investigation into the Population Status of Varanus olivaceus in Alabat Island, Quezon Province......... 45
Report on the occurrence of fruit-eating monitor lizard in the Northern Sierra Madre National Park..... 47
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PROJECT SUMMARY
We have developed a range of non-intrusive techniques to investigate the ecology and
population biology of fruit-eating monitor lizards in the Philippines. We have
investigated the status of the animals in various parts of Luzon and conclude that they no
longer exist in many areas as a result of large-scale deforestation and are now restricted
to fragmented forest in eastern Luzon. Small isolated populations also exist on Polillo and
Alabat Islands in Quezon Province. A new form of fruit-eating monitor lizard was
discovered in the Sierra Madre mountains whose taxonomic status is currently under
study.
Work on Polillo Island has concentrated on identifying key resources for lizards in
degraded forests, comparing population structure in habitats of different quality and
examining the animals’role in the dispersal of Pandanus and Canarium seeds.
Populations persist in moderately degraded forest if suitable shelter trees are present and
key fruit resources available for at least part of the year, but these populations occur at
higher densities and contain very few adult males. Where corridors of non cultivated land
exist between patches they are utilised by the lizards. Evidence was collected suggesting
the lizards are responsible for almost all uphill dispersal of Pandanus seeds and therefore
play an important role in the maintenance of microhabitats that are essential to many
endemic plants, animals and fungi. In May 2006 an Animal Planet documentary about the
lizards and their plight on Polillo was released and shown world-wide.
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Important Note: CLASSIFIED INFORMATION
Early in this study it became apparent that some discoveries about the
distribution patterns of giant frugivorous monitor lizards had the potential
to be misused and lead unscrupulous people to places where they would
most easily be able to catch the animals. For this reason the specific
identification of certain tree species have been withheld. I will supply the
information on request to bona fide fieldworkers
PROJECT BACKGROUND
Giant frugivorous lizards (GFL) occur only in the Philippine Islands. They are an
evolutionary and ecological oddity because they are obligate fruit eaters, extremely large
(>9kg/180cm) and belong to a family of lizards whose other members are exclusively
carnivorous. Despite their size they are extremely secretive animals. Only two species of
GFL are known to science, one (Varanus mabitang) was discovered in 2001 and the other
(V.olivaceus) was described in 1845 but had been the subject of a single study in the
1970s using destructive methodologies that are now considered unacceptable. Both are of
high conservation concern because of their fragile niches and inability to survive outside
their rapidly dwindling habitat of lowland dipterocarp forest. The only other giant lizard
of equal conservation concern is the Komodo dragon, which has benefited from
enormous publicity and conservation efforts. In comparison GFL have received virtually
no attention at all. This report describes the development of non-destructive and nonintrusive methods to investigate baseline biology and population status of V.olivaceus on
Polillo Island, Quezon Province and the application of these methods in other parts of the
Philippines where unknown populations of GFL might still occur.
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SURVEYS ACROSS THE PHILIPPINES
Summary
Investigations in central Luzon suggest that populations still occur in parts of Rizal
Province and that a population in Laguna occurred up to at least the 1960s but is now
almost certainly extinct. A very small population of V.olivaceus still exist on Alabat
Island in Quezon Province and a GFL of undetermined taxonomic status was discovered
in the Sierra Madre mountain range. The animal will be formally described following
molecular analysis in cooperation with Rafe Brown at the University of Kansas. The
known range of GFL suggests that many populations have been driven extinct without
scientists ever having been aware of their presence. Almost all surviving populations are
under extreme pressure because of increasing fragmentation and degradation of lowland
dipterocarp fragments.
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Background
A major aim of this study is to develop survey techniques for GFLs that do not disturb
the animals and do not rely on the lizards’actual presence in the study area. Such an
approach is important when looking for evidence of animals that show a highly clustered
and, without knowledge of the local phenology of resources, unpredictable distribution.
Surveys that rely on finding the animals require very high effort and a large element of
luck in locating the current centres of activity. Inability to find lizards would mean the
results were inconclusive or negative and require follow-up investigations. By surveying
forest understorey for evidence of the animals’recent presence unpredictable factors that
limit current occupancy (e.g. weather conditions, local resource availability, recent
disturbance) can be disregarded. The core assumptions of these methods are that
Pandanus is a staple part of the diet of all frugivorous monitor lizard populations and that
no other vectors regularly disperse clumps of Pandanus seeds on hillsides and ridges.
Early attempts to apply these methodologies outside Polillo are described in the
Appendices and summarised below.
Figure 1. Study sites
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Panay
The known range of V.mabitang is extremely small; it is known from forested areas in the
northwest of Panay but has not been recorded elsewhere on the island. Following reports
of a different type of large lizard in areas of central Panay, Marisol Pedrogosa visited
Polillo to learn techniques in March 2005 and conducted a month long survey in central
Panay in September 2005. No firm evidence that GFL exist in these areas was found and
the lack of Pandanus in forested areas leads us to suspect that the lizards have not
occurred in this region in the recent past. The full report is given as an appendix.
Camiguin Norte
Following reports (based on interviews with hunters and the supposed collection of feces
containing large numbers of Pandanus seeds) of the occurrence of giant frugivorous
lizards on the remote island of Camiguin Norte in the Babuyan group north of Luzon, a
visit was made to the area in March 2005. Pandanus is absent from most forested areas
and the Pandanus accumulations observed were attributed to the above-ground caching
behaviour of rats (a behaviour that has not been observed on Polillo). There was no
evidence of the presence of GFL at any of the sites we visited and if the lizards have
existed there in recent times they must have had a very restricted distribution or been
present at very low densities. The full report is included as an appendix.
Alabat
The small island of Alabat contains two patches of watershed forest that had been
reported to still support a small population of Varanus olivaceus. In September 2005 Dr
Rogelio Sisson (National Museum of the Philippines, Reptile and Amphibian Division)
and Carl Oliveros conducted a survey for the species. Pandanus abundance is high within
forested areas and although no feces were located it seems certain that small populations
still persist within the watershed areas. Dr Sisson will return to the area before the end of
2006 in the hope of procuring a specimen for the National Museum. The full report is
included as an appendix.
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Mount Makiling, Luzon
To compare Pandanus abundance and distribution on Polillo with sites on Luzon a visit
was made to Mount Makiling, Laguna. A day searching the area around Mudsprings
found only a single Pandanus plant of unknown species. According to the late Blaz
Hernandez some areas of Makiling do have high densities of Pandanus and he recalled
that a large fruit-eating lizard was captured in forest behind the Animal Husbandry
building of the University of the Philippines at Los Banos in the late 1950s or early
1960s. So although V.olivaceus may have occurred on Mount Makiling in the recent past,
it can be stated with certainty that its distribution did not include the Mudsprings area.
Rizal Province, Luzon
Interviews with hunters by Matt Yuchek strongly suggest the presence of a population of
GFL in forest east of Montelbarn in Rizal province. We hope to make preliminary field
visits to the area in 2007.
Sierra Madre, Luzon
The northernmost populations of V.olivaceus known are those on Polillo Island and the
adjacent part of Luzon (specifically the UP Land Grant site at Real) which is now entirely
denuded. Auffenberg speculated that the species may occur northwards through the Sierra
Madre mountain range but despite the presence of biologists in the area for several
decades no evidence of the species had been found. In 2004 I saw pictures taken by
Merlijn van Weerd of a large lizard that had been killed and chopped up by a hunter in
Sierra Madre. The pattern of the animal was highly reminiscent of V.salvator but the feet
and claws were large and powerful. The head appeared to be large and the nostril slitshaped but the battered condition of the animal left some uncertainty. In March 2005 I
visited the area with Merlijn and members of the Philippine Crocodile Team for a
reconnaissance visit. The area was being heavily logged and in all areas we visited there
was ample evidence of recent chainsaw activity. Pandanus distribution was clumped but
many trees occurred on the top of the hills and local hunters spoke of a tasty lizard that
ate Pandanus. Later that year Roldan Dugay joined the Polillo Butaan Team as a full time
researcher and spent several months learning techniques on Polillo Island before
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commencing a field study in Sierra Madre. Almost all the areas he has visited are
experiencing disturbance and destruction from teams of chainsaw operators but a
specimen was finally collected from a local hunter under permits issued by the office of
the Protected Area Superintendent of the Northern Sierra Madre Natural Park and the
lizard was deposited in the National Museum of the Philippines. Its taxonomic status is
currently under investigation and full results are expected in 2007. The full report is
included as an appendix. From photographic and other evidence we have eight confirmed
localities for this form in Sierra Madre
Fig 2. New form of giant frugivorous lizard from Sierra Madre.
Extremely wet weather in 2005 had an adverse effect on field work in Sierra Madre and
Panay.
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RESEARCH ON POLILLO
The remainder of the report documents key developments in research methodologies and findings
about the biology and conservation of GFLs, based on intensive research on Polillo Island
Study site
Polillo Island is situated in the Pacific Ocean east of Luzon Island in the northeastern Philippines
(Map 1). The climate is complex but characterised by heavy rainfall through much of the year
with peaks in August and November. The hottest and driest period is March-June, and the coolest
months are December to February. The study site includes the protected Sibulan Watershed
Reserve and adjacent forest fragments, with a total area of approximately 5km2. The site is hilly
(elevations 60-300m) with many streams and swamps in valley bottoms. Local vegetation profiles
are described by Galley (2001) and Clements (2003) and range from apparently pristine (uncut)
forest dominated by dipterocarps to heavily logged habitat with few large trees and virtually no
dipterocarps. The area is bordered and interspersed by agricultural land (mainly rice fields and
coconut groves) (Map 2).
Base camp for the project is the family house of Augusto Zafe who has been a principle member
of the team since 1999. The camp is within ten minutes walk of the edge of the study site. Work
is conducted by a core team (Daniel Bennett, Augusto Zafe, Mang Hil) accompanied by other
forest wardens and visitors (primarily other biologists and veterinary students). Since March 2005
at least two field workers have been employed full time on the project to maintain camera traps
and monitor study sites.
Fig 3. Polillo Island and close-up of the
study area. Forested habitat is dark green
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Study Techniques for GFLs
Summary
Giant frugivorous lizards are extremely shy animals. In some cases capture of individuals
can lead to a cessation of all lizard activity in that area, probably as a result of
chemosensory cues produced by captured animals. Captured individuals have never been
observed to return to the point of capture, even after several years. For these reasons
methodologies that do not rely on capturing animals are essential. They include fecal
collection and analysis (to determine diet, identify activity areas and estimate overall
activity levels and population structure) and use of infra-red triggered camera traps (to
determine key tree resources, levels of intra and inter-specific competition, estimate
population structure and investigate tree use by individuals). These methods reveal that
on Polillo V.olivaceus feeds almost exclusively on three species of animals and 10
species of plants, forages for fruit in trees rather than on the ground and habitually return
to certain trees whenever they are in fruit. The scattered distribution of rare fruiting trees
leads to clustering of individuals for at least part of the year. The lizards are the main
disperser of two important plant genera (Canarium and Pandanus) and seedling
distribution of Pandanus can yield incontrovertible evidence of the animal’s occurrence
in an area even when the animals are seasonally absent. The methodologies developed
pave the way for efficient surveys of other areas that may still contain populations of
GFL and have identified key resources that are essential to the animals’ continued
survival.
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Background
Varanus olivaceus is impossible to study using standard non-destructive methods
employed for other Varanus lizards (e.g. Traeholt 1995, Sweet 1999, Bennett 2000,
2002) because they spend almost all their time high in the canopy, cannot be attracted to
baits and are highly sensitive to disturbance. The only previous study of the species
(Auffenberg 1988) relied on the use of dogs to capture individuals which resulted in very
high mortality. The lack of acceptable methodology left little incentive for field
researchers to follow up on Auffenberg’s work and for almost 20 years the species
attracted no interest. In 1999 and 2001 a study of V.olivaceus (known locally as butaan)
was carried out as part of the Oxford University / University of the Philippines at Los
Banos Polillo Islands Project to attempt to develop non-destructive and inexpensive
methodologies that could be employed by local workers (Bennett 2001, Bennett and
Hampson 2003).
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Capture of Individuals
Varanus olivaceus cannot be attracted to baits effective for other Varanus species and the
only way specimens could be caught was with dogs (Auffenberg 1988). We have
developed several methods for the safe capture of the lizards (Bennett et al. 2001) and an
efficient way of baiting the animals. However evidence from a variety of sources (see
below) suggests that capturing individuals over 4kg causes long-term changes in their
activity areas and can temporarily alter the behaviour of all sympatric individuals. As a
result no animals have been purposely caught since 2002.
The Importance of Non-Intrusive Methodologies
One of the most striking aspects of the behaviour of V.olivaceus is its extraordinarily
shyness and sensitivity to disturbance.
Spool and line data indicates that whilst animals under 2.5kg quickly recommence
feeding behaviour close to (but rarely at) the point of capture larger individuals always
leave the area, either immediately or after a 1-17 day period in a shelter tree at the release
spot. They never return during the tracking period (maximum of approximately 35 days))
and there is no evidence from camera trap data that captured individuals ever return to the
point of capture, although other individuals often make repeated visits to the same trees.
It is suggested that the experience of capture causes individuals to avoid the capture area
and that large individuals (presumably with good knowledge of alternative resources)
prefer to omit the capture point from their activity areas.
When V.olivaceus are aware of the presence of people they hide themselves by moving to
the opposite side of the tree trunk, flattening their bodies against the bark or taking cover
in dense foliage. Animals over 1kg remain hidden for longer than team members have
had the patience to watch them (up to five hours). Smaller animals sometimes descend
the trunk, albeit cautiously, even when groups of people are standing at the base of the
tree. They may make several forays up and down the trunk before eventually descending
to a level where they can be noosed.
For population studies capture of any individuals is best avoided. If the interpretations
given above are correct it can be surmised that capture causes temporary or permanent
movement away from the point of capture and that disturbance of a single individual can
14
result in avoidance behaviour by the entire population for periods of days or weeks. In
this case non-destructive methods are clearly intrusive and even non-intrusive methods
have the potential to cause disturbance.
Feces
Summary
Feces are currently yielding valuable data on seed dispersal dynamics and ontogenetic,
seasonal and annual differences in dietary composition. They also have the potential to
allow entirely non-intrusive and highly accurate measurements of population size and
structure, movements and feeding habits of individuals and levels of stress at both the
individual and the population level using molecular markers for microsatellite DNA and
corticosterone assays. Both would have important implications in the study of
populations in highly fragmented and disturbed areas. Possibilities for employing these
methodologies are currently being investigated.
Background
The vast majority of studies of diet in Varanus lizards have been conducted by
dissections and, prior to this study, all that was known of the diet of V.olivaceus was
based on the dissection of 112 individuals by Auffenberg (1988). Methods employed for
other species include fecal recovery (Bennett 2000), direct observation (Auffenberg 1981,
Traeholt 1994) and stomach flushing (Bennett 2004). Early in this study it became
apparent that the feces of Varanus olivaceus were almost always easily distinguished by
size and composition and could be detected with much less effort than it took to locate
animals.
Methods
Searches for feces are carried out informally during the course of other activities or along
flexible “Ariadne” transects (see below). Locations of feces are labelled with a ribbon tag
for subsequent GPS mapping, age of the sample is estimated and the numbers and types
of prey items present recorded. Seeds are counted individually whilst crab and snail
fragments are always counted as 1 unless they clearly represent more than one individual.
15
In the case of flexible transects workers are fixed with a cocoon bobbin containing 320m
of thread finish when the thread has expired. Width of these transects is taken as 2m to
approximate the field of view of the searcher. Flexible transects have several important
advantages over traditional straight line approaches which produce a random sampling
area that includes trees and other obstacles and ignore differences in gradients. Searching
for feces along straight line transects tends to yield very low results because they rarely
intersect with paths taken by animals; most of the search is conducted in areas where, for
various reasons, feces are unlikely to be encountered. Using a flexible transect allows
sampling effort to be controlled whilst giving the worker the freedom to utilise
knowledge of topography and animal paths to maximise yields. Other advantages of the
method over random searches are that areas already surveyed by other workers can be
easily avoided and disorientated workers can easily retrace their route to the start of the
transect.
For dietary analysis the study area is divided into sites which consist of discreet
fragments of forest or one or more hills within a larger block of habitat. Areas are visited
at irregular intervals and care taken not to visit revisit sites that appear to be densely
populated more than once every 14 days to avoid excessive disturbance.
Results
A total of over 1,100 fecal samples have been recorded from the Polillo study site,
representing perhaps the largest dietary dataset for any single population of reptiles.
Seasonal and spatial variation: Distributions of feces suggest that populations are most
scattered from November to March (when animals are feeding largely on fragrant, lowhanging fruit available in small quantities on scattered trees) and tend to cluster around
rare, heavily fruiting trees from approximately April to October. Activity (or at least
frugivory) may be reduced during the cooler months of December and January because
few feces are found. Diet shows considerable variation between hillsides, seasonally and
between years. For most fruit species utilisation appears highly correlated with
availability. Pinanga is available throughout the year but only eaten during certain
(irregular) periods suggesting that it is less preferred than other fruits.
16
250
200
150
100
50
0
<0.5
51-100
101200
201300
301400
401500
501600
601700
701800
Original fruit mass (g)
Fig 4. Size distribution of feces based on estimation of original fruit mass.
Note large outliers.
Population structure: Estimates of population structure from feces agree well with
estimates from camera trap data. A direct measure of population size is not possible from
fecal data because many samples can come from the same individual. Smaller animals
make more feeding forays than larger ones and probably defecate more regularly and
over a smaller area.
However the shape of size distributions can be used to infer
population structure if it is assumed that larger feces are easier to find than smaller ones.
A striking characteristic of fecal size distributions is the presence of a small but persistent
number of unusually large outliers (Fig 6). Evidence from camera traps indicates that at
least one exceptionally large (>10kg) individual is present in the study area.
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Fig 5. An extremely large V.olivaceus captured on camera trap.
Comparison with mainland population: Overall plant diversity might be expected
to be lower on Polillo because of its small size and distance from mainland Luzon, but
there is no evidence that this is the case (Clements 2003). On Polillo plant species
richness in the diet of V.olivaceus is similar to that reported by Auffenberg (1988) in
Camaroan but the species composition shows important differences. The only plant
important in the diet of the Caramoan sample that is not known to occur on Polillo is
Spondias pinnata. Five species of Aglaia are known to occur at the Polillo study site but
no fruit have been found in lizard feces. Pinanga an important item in the diet of lizards
on Polillo is conspicuous in its absence from Auffenberg’s study. Over 100 species occur
throughout the Philippines and the genus is reported to be most diverse in limestone
regions. It is very unlikely that they do not occur within his study area but none were
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recorded in the diet nor is the genus mentioned in the text. If Pinanga is abundant in the
Caramoan area the heavy dependence of the Polillo population on the fruits might be
indicative of habitat that is poor in resources. That Gnetum was present (“common”) in
the Caramoan area but was absent from Auffenberg’s dietary sample although it is
common in the Polillo sample is more difficult to explain. Possibly preferred fruits exist
in Camaroan or local Gnetum are somehow unpalatable to the lizards. Unfortunately the
samples obtained by Auffenberg were not preserved (W. King, personal communication)
and the possibility that some of his identifications are erroneous cannot be discounted.
Seed dispersal: Data suggests that V.olivaceus is the main disperser of Pandanus and
Canarium seeds on Polillo. Although rats occasionally disperse Pandanus and Canarium
by failing to destroy them (fig. 10) all seeds deposited by lizards germinate readily.
Canarium seeds are also dispersed by a few species of birds on Polillo (hornbills and
pigeons) but in very low numbers (according to estimates from hide observations and
camera traps and from accounts in the literature).
In the absence of animal vectors Pandanus are dispersed by water and their usual habitats
are swamps, waterway and coasts. On Polillo Pandanus is more abundant on hilltops than
along streams and densities are extremely high. Dispersal of Pandanus is of particular
importance because of increasing evidence that the plants act as essential microhabitats
for many unique fauna and flora. They support a vast number of unique fungi, some
insects, and in Madagascar are thought to be the only egg deposition sites of many
species of amphibians (Lehtinen 2001). In this respect it is noteworthy that the two
vertebrates endemic to Polillo are collected almost exclusively from Pandanus habitats.
The gecko Pseudogecko smaragdinus is known as Butin na Pandan in Tagalog and strong
empirical evidence exists of the relationship between Pandanus abundance and the
occurrence of the frog Platymantis poliloensis (Hampson 2001). No studies of the
invertebrate, floral or mycological communities of Pandanus have ever been undertaken
on Polillo but such studies would unquestionably lead to the discovery of many new
species.
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Figure 6. Pandanus species from Polillo
Figure 7. Varanus olivaceus and Rattus everetii feeding on Pandanus
Many clumps of young plants are found growing uphill of any possible parent tree –
strong evidence that the lizards are acting as their dispersal vectors. Visits to other areas
inhabited by GFL confirm that Pandanus is a common element among hill top floral
communities in Panay (around the type locality of V.mabitang) and in north-eastern
20
Sierra Madre (locality of a currently unclassified form of GFL - see below). This suggests
that the lizards’ feeding behaviour maintains high genetic diversity and density of
Pandanus which in turn allows the persistence of unique faunal and floral elements by
providing essential microhabitats. Over evolutionary time the effects on populations of
adult Pandanus plants of the loss of animal dispersers would be a very slow process but
the appearance of new clumps of Pandanus uphill of parent plants would cease
immediately and it is that characteristic that makes the study of Pandanus distribution an
extremely powerful tool in the identification of areas that still have, have recently lost, or
have never been home to populations of GFLs. In the near future we hope to investigate
the genetic diversity of Pandanus populations in areas where they are regularly dispersed
by lizards or only rarely dispersed by rats using molecular techniques.
Camera and Video Camera Traps and Direct Observation
Background
Camera trapping has rarely been used to monitor reptile populations, however it has the
potential to provide valuable information on resource use, levels of competition, changes
in population structure through time and in individuals with age. With sufficient
knowledge of the available resources it should also be possible to track individual’s
movement according to preferred fruit availability. Video camera trapping of low
hanging fruit facilitates direct observation of foraging behaviour and estimation of
individual fruit intakes. The discovery of trees with very high visitation rates suggested
that direct observation from camouflaged hides might also be worth investigation. In
particular it could be used to test the efficiency of camera traps, look for evidence of
disturbance from camera flash or sound, investigate the potential for filming animals for a
documentary and test the hypotheses that 1) mature individuals are often too big to forage
on thin branches and 2) lizards prefer fruit on the ground to fruit on branches.
Equipment and Methodology
The units (Trailmaster 550 and Canon AE1 camera) cost almost $500 each and trials
were conducted with various other models priced between $50 and $350. None were
satisfactory, at least partly because the camera and sensor are combined units and there
21
are great advantages in being able to place the sensor closer to the tree than the camera.
Furthermore pictures are best taken in portrait orientation to include as much of the tree
trunk as possible. Other advantages of Trailmasters are long battery life (at least ten
months from 4 X D cell batteries for the sensors, 3 months from 1 CR123A battery for
the cameras), short camera delay (minimum 6 seconds), superior resistance to rain,
precise control of sensitivity and on/off times. The primary disadvantage is that they are
rather complicated to program and the manual is not easy for many co-workers to
understand. The project currently owns 16 Trailmaster 550 camera traps purchased with
the BP grant and has two 770V video traps on loan from Katie Hampson (Princeton
University). We have lost two camera traps to theft. Within 14 months of purchase none
of the Trailmaster units were functioning and are currently under repair in the US.
Traps are set at fruiting trees (occasionally at shelter trees) using the settings P=2 Pt=10
Cd = 0.1. The sensor is placed 2-3m from the trunk pointing slightly down to cover
activity at a height of 0-2m depending on tree type. Colour print film is used rated at 1001600 ASA. Cameras are usually set in portrait orientation and in “panoramic mode. This
produces a narrower image but has the important advantage that the date/time
information is on unexposed film and is therefore easy to read. Sometimes this
information is obscured by bright backgrounds in standard mode. Because of low light
levels in the forest and 24 hour operation flash was used on almost all films up to 2004.
Experiments to test for differences in number of events obtained with and without flash
have been inconclusive but direct observations from hides suggests that some lizards
freeze when the flash is triggered and occasionally leave without feeding. Attempts to
eliminate flash use using very high speed film (800 and 1600) were generally
unsuccessful (see below). Because no lizards were ever recorded during the hours of
darkness traps have operated only from 0615 to 1830 since 2004. Checking traps requires
balance between ensuring cameras do not run out of film and minimising disturbance at
the area. Logistical reasons also prevent regular checking during some periods and this,
combined with failures due to wet weather and rodent damage means that monitoring
periods are often incomplete.
22
Collected films are labelled in situ and developed when time permits. Prior to 2005 films
were developed and printed at commercial establishments in Manila and electronic scans
made of negatives that contained events. Attempts to save money by scanning negatives
without a print guide were extremely time consuming because scans were made on a
Minolta F-2800 machine that had to be manually loaded (36 exposures took 4-5 hours
and required constant supervision). As a result consumable costs were considerable
(approx $6.50 for film, processing and printing). The purchase of a Nikon Coolscan 5000
scanner and SA-30 bulk film loader in 2005 allows uncut rolls of negatives to be scanned
automatically, greatly reducing the time involved and eventually saving money by
eliminating printing costs. However the high cost of the equipment ($1500) means that
cost savings are not expected until early 2007.
Images containing events are scanned at maximum resolution resulting in files of about
30MB from the Minolta and 67MB from the Nikon scanner. Images are examined to
estimate the size of the individuals using a comparison image of the tree with a 10cm
scale held against the trunk) and to determine identity. Two people independently attempt
to identify individuals from pictures based on size, pattern and scars or injuries
(unfortunately the tail notches given to captured individuals are too indistinct to be
visible on camera trap pictures). Where their interpretations differed the series is reexamined and the most probable identifications agreed upon. The Polillo population of
V.olivaceus is perhaps the least patterned of any of the races known. Except when they
are very young most individuals have very indistinct markings. Identifications are further
complicated by a loss of pattern as time since last skin shed increases, an increase in
pattern when the lizards are wet and inconsistent exposure depending on time of day and
position of the sun. Identification is therefore a lengthy process that often requires careful
manipulation of image characteristics. Nevertheless positive identifications have been
made for most events at three key trees that have been monitored during every fruiting
period since 2003 and analysis of the entire dataset up to July 2006 is expected to be
completed by the end of the year.
23
Results
Camera traps: 245 rolls of film that have been analysed taken at 41 trees have recorded
616 events (defined as a single visit to a tree) comprising of 336 images of lizards
climbing trees and 475 of lizards descending. In addition images of skinks (<10g), rats,
Varanus salvator, civet cats, monkeys, bats and birds have been obtained. Lizard activity
was recorded at 29 trees and 106 films (43%) contained one or more event (mean 5.7, +
5.9, range 1-24). Trees that were visited received a mean of 0.82 visits per day (+ 0.7,
range 0.04-3 visits per day). The least heavily utilised trees were shelter trees typically
used for a few days by a single individual. The most heavily utilised trees were rare,
dioecious, fruiting trees with a heavy crop and long fruiting season. These trees are
probably visited by all members of the local population at least once. In several cases
where such trees occur in degraded habitat they appear to be the only reason why the
areas are visited by lizards. I hypothesize that removal of these trees would result in the
final disappearance of V.olivaceus from the area. To date none of these trees within the
study areas have been destroyed but two are likely to be lost through slash and burn
clearing in the next couple of years.
Camera trapping supports findings from spool and line tracking that V.olivaceus pick
fruit from branches rather than collect it on the ground. Mean time spent in fruiting trees
was 20.5 minutes (N = 223). Some short visits (<5 minutes) are probably not feeding
events but either freezing or fleeing behaviour associated with camera flash or lizards
climbing a tree that is already occupied by another (always larger) individual and leaving
prematurely. Sometimes lizards arrive at a tree separately and leave together and
sometimes they arrive at the tree within minutes of each other. Lizards are more likely to
meet conspecifics at fruiting trees than at shelter trees. Such encounters are rare for most
of the year but peak sharply in July and August, which is believed to correspond to the
mating season (Auffenberg 1988).
24
Figure 8. A pair of V.olivaceus captured on camera trap.
Small individuals tend to visit trees regularly (up to four times per week) whilst larger
animals make fewer visits and the largest animals are the least frequent visitors. This may
be because larger animals are able to consume many more fruit in a single visit and make
fewer feeding forays as a result, or because larger individuals also forage at trees that are
unknown to us. An alternative explanation is that young lizards return regularly to
fruiting trees in order to reinforce their memory of its position
For more mobile frugivores information centre based scenarios have been proposed
whereby individuals have the opportunity to learn the position of resources from others.
Such behaviour is probably normal in birds, bats and primates that feed in groups. No
such system has ever been proposed for a lizard but it seems probable that certain trees
25
act as information centres for V.olivaceus by carrying chemosensory details of recent
visitors. In this scenario animals would search for trees used by conspecifics rather than
trees containing fruit, and animals moving on resource trees have the option of leaving
more or less clues of their visit. It is hoped to test some of these ideas using direct
observation from hides in 2007.
Error Sources: Camera traps fail to record all visits to trees because some lizards take
routes to the fruit source that evade the sensors; e.g. jumping to or from an adjacent tree,
climbing vines or climbing the back of the trunk. This may be personal preference or in
order to avoid noise and light from cameras. Anecdotal observations made from
camouflaged hides of individuals foraging at trees with camera traps indicate that some
individuals freeze for short periods when camera traps are triggered and one was
observed to jump off the trunk and run away. Within the study areas many lizards are
now well acquainted with camera traps and appear to ignore them entirely. A quantitative
measurement of response to electronic camera flash and noise should be possible by
observing the behaviour of naive animals of different sizes to camera trap operation using
a (silent) video camera.
Video Traps: Most trees that have high visitation rates have canopies that are largely
obscured from the ground making use of video camera impractical. Setting video on
trunks yields very short sequences of animals ascending the tree but rarely captures the
descent (because of the lengthy (3-5 second) start up time. Such videos are easy to obtain
and show that lizards regularly tongue flick the bark as they climb. However video traps
are most enlightening when the trigger and camera can be aimed directly at low-hanging
fruit such as Pandanus. Attempts to capture feeding behaviour at Pandanus trees started
in 2002 but because of their unpredictable fruiting patterns and the fact that most fruiting
specimens are not visited by any lizards but all are visited by rats that like to chew cables
no footage was obtained until 2004. The results were well worth the wait, because not
only do they constitute the first moving images ever taken of a frugivorous monitor lizard
in the wild they also shed light on why V.olivaceus is able to utilize a fruit that very few
other animals consume. Removal of ripe Pandanus drupes often requires considerable
26
strength and the only “perching area” is a hard shiny trunk that few animals can grip.
V.olivaceus removes Pandanus fruits by holding the trunk with the hind feet only and
reaching out with the head and forelimbs to the syncarp. When a suitable drupe has been
tongued and touched the lizard grasps it in the mouth and attempts to pull it from the
syncarp by flexing the neck and back. Small individuals find it very difficult to remove
Pandanus fruit and may spend 15 minutes removing a single drupe, falling out of the tree
many times in the process. Some of the sequences obtained were highly entertaining, so
much so that we were able to persuade a media company that it would be possible to
produce a documentary about the lizard (see below). Video trapping also allows a precise
count of how many fruits are eaten by individuals that has to be inferred from locally
collected fecal data for still camera traps.
Camouflaged Hides: Ameristep camouflaged hides are set at least several days before
first occupancy and observers equipped with binoculars and a video camera are in place
by 7am and leave between 5 and 6 pm (depending on distance from base camp).
Observers can drink but cannot eat or wear mosquito repellant. Conditions in the hide are
most usually described in terms best summarized as “hostile”. Discomfort from heat and
lack of ventilation are compounded by extremely high mosquito densities. However
almost all observers have been rewarded with views of an animal that very few people
have ever seen and some useful data has been generated. With the exception of Grewia
no fruits have been observed to be eaten from the ground. Lizards sometimes eat one or
two Grewia fruits from the ground before climbing the tree but even the largest animals
can manipulate thin branches with apparent ease.
The considerable amount of data generated from camera traps is under analysis and a
preliminary paper on the results is hoped for in 2007. Functioning camera traps from the
project will be used throughout the Philippines with the aim of capturing images of
endemic species that have never previously been photographed in the wild.
27
Education, Training and Development
The lack of any official enforcement of laws regarding logging and hunting in the
Philippines is compounded by considerable population pressures and dire economic
conditions. Thus although education efforts on Polillo have been extremely effective
people appear to have little choice and no disincentive but to clear existing forest for
agriculture and remove hardwood trees for timber. We believe that the activities of the
Polillo Butaan team have almost entirely eliminated hunting of animals in this area and
the destruction of habitat within the watershed zone. However connecting areas of forest
are being destroyed at a very rapid rate. Key corridors between forest fragments have
been identified and local landowners made aware of their importance. Over 100 trees that
are of particular importance (to butaan or other vertebrates) have been identified in areas
that are under immediate threat and are protected by people living locally.
A significant achievement has been to dissuade local people from taking dogs into the
forest. Almost every household owns at least one dog and most lizards are caught
following their discovery by dogs in the forest. Dogs on Polillo are adept at flushing out
animals and attack even large pythons without fear. Polillo members of the project have
worked tirelessly to persuade people to avoid taking dogs into forested areas because of
the damage they cause. We have not seen a single dog in the watershed forest since 2005.
Despite the exceptionally high levels of endemism in the Philippines the country’s
wildlife is rarely portrayed in world-wide media. As far as I am aware the only
documentary about Philippine fauna with world-wide distribution was a film about the
Philippine eagle. A film crew from Steel Spyda (UK) visited Polillo to make a 60 minute
documentary about V.olivaceus and the role of the Polillo Wardens in its conservation.
The documentary (“Butaan – The Lost Dragon”) was released in November 2005 by
Animal Planet. Unfortunately the documentary contained multiple errors and failed to
acknowledge any of the project’s supporters. Animal Planet agreed to reedit the
documentary and a much improved version was released in the USA in May 2006.
28
Students and researchers from eight institutions (UP Los Banos, UP Dilliman, Ataneo
University, Philippine Crocodile Project, St Tomas University, Cebu Biodiversity
Project, Katala Foundation, Mindoro Reptile Foundation) have visited Polillo to become
acquainted with the techniques. Selected students on Polillo have also been trained.
To publicise methodologies presentations were made to students and staff of the
University of the Philippines (Los Banos), University of the Philippines (Dilliman),
Wildlife Conservation Society of the Philippines and the University of the Philippines
Zoological Society. I also gave presentations at the Fourth International Symposium on
Frugivores and Seed Dispersal (Brisbane), Chester Zoo education and curatorial staff,
Herpetological Taxon Advisory Group Meeting of the AAZA (Houston), Third World
Congress on Varanids (Bonn) and Conservation International Headquarters (in
Washington D.C. - attended by two people!).
The Sibulan Watershed area contains the only pristine lowland dipterocarp forest on
Polillo and is one of the last such fragments in southern Quezon. It contains all the known
species of animals and plants that are endemic to the island. Despite the area’s
importance facilities for visiting scientists have been very rudimentary. We installed a
generator at base camp that has been of great benefit to both local people and visitors.
29
CONCLUSIONS
V.olivaceus is an ideal flagship species for conservation in Philippine forests because
direct action to ensure its continued occurrence would safeguard most other local fauna
and flora. At present very little of the range of the species has been surveyed and
available information suggests that the animals have disappeared from most lowland
areas throughout their former range. Surveys of remaining forest patches should therefore
be a priority. Inexpensive, low effort and reliable survey techniques that do not disturb
the animals have been developed, most of the resources important to GFL can be
identified and mapped, and patterns of use for many resources can be predicted. I
anticipate that it will also be possible to determine areas previously or currently occupied
by V.olivaceus based on the distribution of Pandanus trees within them (see above and
below).
An ultimate aim of this study is to mitigate the effects of hunting and logging activities
and to eventually facilitate the re-introduction of GFL into areas from which they have
been extirpated. To this end considerable effort has been put into determining which
resources are important to V.olivaceus and how the needs of the human population
conflict with those of the lizard.
Effects of fragmentation and degradation
The implications of shrinking and increasingly fragmented habitat for a large immobile
frugivore are intriguing. Most fragments in the study area are too small to support
constant supplies of the required fruit resources and so animals move between patches,
usually through corridors of dense ferns. Where such corridors do not exist the animals
would be obliged to move through cultivated habitats where they are at high risk of
detection by people or dogs. That they are sometimes forced to is illustrated by locals
recollections of animals cornered in coconut trees, although such events are rare.
The situation on Polillo Island allows the processes through which lizards are driven
locally extinct to be identified. The highly complex forest/ farm mosaic shows great
30
heterogeneity in terms of fragmentation, isolation and resource abundance. A number of
areas that supported V.olivaceus in 1999 no longer do so, because they have been totally
destroyed, have lost key resources, are subject to regular disturbance or have lost
corridors and become completely isolated.
Forest patches on Polillo are small (maximum 4km2), fragmented and virtually all
degraded to some extent. As a very large and flightless animal with a narrow dietary
breadth, V.olivaceus maybe more sensitive to habitat fragmentation than any other
frugivore in the Philippines. Populations on Polillo have been subject to extreme pressure
since the 1950s as a result of intensive and wide-scale logging and the surviving animals
are restricted to very small patches of largely degraded habitat. Although habitat loss now
occurs at a much lower rate it is ongoing in parts of the study area outside the Sibulan
Watershed Reserve. At least several hectares per year of forest are cleared for coconuts
through slash and burn and an unknown number of timber trees are extracted with
chainsaws. Evidence suggests that most timber cut is used locally for construction. Based
on the number of new houses built in the area and size of chainsaw stumps that I
encounter, timber extraction is estimated at a minimum of 60 trees per year. These forest
patches are privately owned and, in many cases trees are taken without the landowner’s
permission. Many landowners spend most of the year away from Polillo and rarely visit
their forests.
Chainsaw operators preferentially remove the large emergent trees used for shelter by
V.olivaceus. In general loggers prefer trees near the bottom of hills (for ease of
extraction) whilst lizards prefer trees close to hill ridges (perhaps for thermoregulation).
In the absence of these trees lizards shelter in the canopies of smaller trees which are
invariably dense with vine thickets and other epiphytic vegetation. Preferential logging
rarely destroys food resources (unless they are destroyed in the process of logging other
trees) but it increases distance between shelter and food trees which makes detection by
predators more likely. Some areas of forest contain no shelter trees of a suitable size for
large individuals but are still visited because they contain important fruit resources.
31
Conversely there are few areas with abundant shelter trees that lack sufficient fruit
resources (for at least part of the year) to support V.olivaceus populations.
V.olivaceus is in no way territorial and activity ranges regularly overlap. For about five
months of the year populations are largely clustered around a few rare fruiting trees.
These trees are considered a very important resource because they supply many members
of the population with fruit throughout the reproductive season and may play a key role
in social interactions at this time. Protection of key resource trees in marginal habitats
and the maintenance of uncultivated corridors connecting them to other habitat fragments
are key conservation priorities
Demand for timber directly affects lizard populations by removing trees suitable for
sheltering adult individuals. As densities of these trees decreases encounters between
people and lizards increase in frequency, especially on hills that also contain important
fruit resources. Shelter trees on particular hillsides are therefore much more important
than similar trees elsewhere and these sites need to be considered priority areas. On
Polillo local landowners are receptive to the idea of setting aside specific hillsides that are
important to local fauna and flora but claim that because most logging is done without
their consent they have little control over which trees are taken. For Polillo at least,
effective conservation strategies depend most on the goodwill of local people and least on
legislative protection
Hunting
V.olivaceus is a highly esteemed food item for people throughout its range. Even people
who do not know that the butaan is a lizard often know that it is delicious and it is by far
the most commonly heard adjective when local people are talking about the animal.
Using a well trained dog and a very experienced team of ex-hunters it took us an average
of 20 hours in the field to catch a single specimen of Varanus olivaceus. Spool and line
data indicates that the animals are on the ground for as little as 25 minutes per week and
spend almost all of their time in large dipterocarp trees where they are impossible to spot.
Catching an animal requires that it is surprised on the ground and caught before it can
ascend a large tree. Thus population size, distance between resource trees and the density
32
of trees too large to be cut down with a machete are all important factors in determining
how much effort is required to catch an animal. Hunting the animals with traditional
techniques is very labour intensive and usually individuals are captured opportunistically.
Most animals captured by people on Polillo are disturbed by dogs and take shelter in trees
from which they can be recovered easily. Other individuals are caught in noose traps and
although these have been largely eliminated from the study area because of the regular
presence of Ecology Wardens it doubtless continues elsewhere. Auffenberg (1988)
estimated that 240 individuals were captured per year throughout the entire range of the
species, and although this is certainly an underestimate (because more animals than this
reach Manila for the illicit animal trade) in good quality habitat the species is encountered
too infrequently for hunting to make an important impact. In degraded areas the animals
become much easier to capture, particularly if many individuals rely on the same resource
because resultant clustering makes detection more likely and the lack of shelter trees
means detected individuals are less likely to escape.
Future Work
Developing a Diet for Captive Animals
A highly relevant application of our knowledge of the feeding ecology of V.olivaceus
would be in the development of suitable diets for captive populations of GFL. Most
documented captive animals have been confiscations held by zoos although a few have
been traded with CITES certificates in the USA and a small but thriving black market
appears to exist in Asia, Europe and North America. However, only two captive breeding
events have been reported, both producing a single hatchling and only one of which
survived more than 48 hours (now 15 months old at the Avilon Zoo, Montelbarn). The
vast majority of captive animals die within 12 months and the unanimous opinion of vets
in the Philippines acquainted with captives is that they are very susceptible to gout-like
afflictions that are attributed to a highly proteinaceus diet. Although captives have been
known to accept sugary fruits such as grapes and figs, no suitable substitutes for the oil
rich staples of their natural diets are available. In the absence of a suitable diet attempts to
breed the animals in captivity look doomed to failure. However there is no doubt that
captive breeding programs would be the only practical conservation strategy for some
33
extremely small and completely isolated populations of giant frugivorous lizards (e.g. the
Alabat Island population, populations that may still exist on Calaguas, Lahoy, Rapu Rapu
and other islands, as well as many surviving forest fragments in the provinces of Quezon,
Laguna, Rizal and Montelbarn on Luzon. A captive breeding population of V.mabitang
(known only from forested fragments in the northwest of Panay would certainly be highly
desirable (the species is currently unlisted but amply satisfies IUCN criteria for EN
listing).
The biggest obstacle to providing suitable fruit is that they are only accepted by the
lizards when in a perfectly ripe state but remain in that state for very short periods,
making transport of fruit even within Luzon problematic. In cooperation with zoo staff
entrusted with holdings of V.olivaceus we are trying to develop extracts of fruit important
in the diet of wild animals that have a longer shelf life and can be used to supplement
artificial diets. Once the problem of feeding GFL has been overcome the prospect of
being able to breed them in captivity will become a reality.
Molecular Studies of Feces
DNA of Varanus olivaceus, Canarium and Pandanus species can be extracted from feces
collected on the forest floor and could be used to identify individual animals and plants,
enabling precise monitoring of individual and populations and quantitative measurement
of the lizards’ efficiency as a seed disperser. We hope to investigate the potential for
using microsatellite markers in the near future.
Corticosterone assays from feces have been used to measure stress levels in many
animals and would be particularly pertinent to the study of GFL because many
populations appear to survive only in marginal habitat. Recent work has demonstrated
that fecal samples must be stored at low temperatures to yield accurate measurement of
corticosterone levels. At present such facilities do not exist but the recent provision of an
electricity supply means that refrigerated storage of samples may be possible in 2007.
34
On Polillo
Current work on Polillo is aimed at preserving corridors between fragments and assessing
the role of V.olivaceus in the dispersal of the plants it feeds on.
In Sierra Madre
In the near future we hope to establish a new team to conduct research in the Sierra
Madre Mountains and the remaining forests fragments of Aurora Province.
Elsewhere
A number of priority areas in central and northern Luzon, Samar, Panay and other islands
in the Sibuyan Sea have been identified that should be surveyed for the presence of GFL
as soon as possible. Subject to funding we will attempt to visit as many of these locations
as possible in 2007.
Through vigorous publicity campaigns that include world-wide television and local
publicity it is hoped to raise the profile of these poorly known animals and generate
efficient community-based conservation strategies that are of benefit to both lizards and
people
35
Team Members 2005-2006
Daniel Bennett (Polillo, Camiguin Norte, Sierra Madre)
Roldan Dugay (Sierra Madre, Polillo)
Carl Oliveros (Camiguin Norte, Alabat, Polillo)
Marisol Pedrigosa (Panay, Polillo)
Mark Reyes (Camiguin Norte)
Maxim Rosarios (Polillo, Camiguin Norte)
Gil Sopranes (Polillo)
Augusto Zafe (Polillo)
Katie Hampson (Polillo)
Jimmy Pasion (Polillo)
Maria Christina P. Resurreccion (Polillo)
Harvey Garcia (Pollillo)
Alice Clarke (Polillo)
Matt Ychek (Rizal)
Rogelio Sisson (Alabat)
Thanks
Augusto Zafe and family, Katie Hampson, Vicente Yngente and family, William
Oliver, North of England Zoological Society, Fauna and Flora International, BP
Conservation Programme, Birdlife International,, Cincinnati Zoo, Columbus Zoo,
Dallas Zoo, Los Angeles Zoo, Pittsburgh Zoo, Kurt Auffenberg, Wayne King,
William Bulalacao, Chloe Galley, Dennis Olaguer, Tom Clements, Edmund B.
Rico, Mark Reyes, Jake Gaw, Arvin Diesmos, Neilson Donato, Emerson Sy, Neil
Hendrix, J.C. Gonzales, Mimie Ledesma, Liza Dans, Chris Turno, Blas Hernaez,
Winston Card, Letty Aufuang, University of the Philippines (Los Banos),
Aberdeen University, Leeds University, Oxford University, DENR (Polillo), Tata
Remy, Mang Pio, Mang Hil, Mang Rudy, Mang Perrio, Pido Bulalacao, Mang
Jimi, Matias Bulalacao, Lito Bulalacao, Ricky Bulalacao,Christian Zafe, Eliazar
Bulalacao, Matt Watson, Philip Alviola, Carl Oliveros, Steel Spyda, Ruston
Hartegen, Matt Watson, Maren Gaulke, Eberhard Curio, Montelbarn Zoo, Hans
Hogberg, Viper Press, Martin Wikelski, Steve Compton, Sandy Duncan, Merlijn
Van Weerd, Danford Threads Ltd, Leonardo Co, Rafe Brown and Steve
Compton. Thanks to enormous goodwill and great assistance the project has
suffered few logistical difficulties.
36
Financial Account
Item
Cost (US$)
12 camera traps
6800
Generator and fuel
935
Central Luzon Projects
300
Alabat Project
500
Camiguin Norte Project
3000
Sierra Madre Project
4450
Panay Project
2100
Wages for local workers-Polillo
4200
Honorariums for local researchers
2500
Food-Polillo
1677
2 flights Manchester-Manila return
2453
Medical, first aid, insurance-Polillo
1226
Camera film, processing, printing
916
Transportation
881
Communications
700
Misc. equipment
425
Total
Additional funding from Chester Zoo, Cincinatti Zoo and FFI
37
33063
References
Auffenberg, W. 1981. Behavioural Ecology of the Komodo Monitor. University of
Florida, Gainesville.
Auffenberg, W. 1988. Gray’s monitor lizard. University of Florida Press,
Gainesville.
Bennett, D. 2000. Preliminary survey and status report for Varanus olivaceus on
Polillo Island. In Bennett, Daniel [Ed.]. Wildlife of Polillo Island, Philippines.
University of Oxford - University of the Philippines at Los Banos Polillo '99
project. Final report. Viper Press, Glossop. 2000: 1-174. Chapter pagination: 927.
Bennett, D. 2000. Preliminary data on the diet of juvenile Varanus
exanthematicus (Sauria: Varanidae) in the coastal plain of Ghana. Herpetological
Journal 10 (2):75-76.
Bennett, D. 2000. The density and abundance of juvenile Bosc’s monitor lizards
(Varanus exanthematicus) in the coastal plain of Ghana. Amphibia-Reptilia
21:301-306.
Bennett, D. 2002. Diet of juvenile Varanus niloticus (Sauria : Varanidae) on the
Black Volta River in Ghana. Journal of Herpetology 36 (1): 116-117.
Bennett, D. 2004. Varanus exanthematicus. In E.R. Pianka, D. R. King and R. A.
King (eds) Varanoid lizards of the world.. Indiana University Press. pp 95-103
Bennett, D. and K. Hampson. 2003. Further observations of Varanus olivaceus
on Polillo. In K. Hampson et al. Wildlife and Conservation in the Polillo Islands.
Final Report. Multimedia CD (ISBN 1-904589-00-6) Viper Press, Glossop.
Bennett, D., K. Hampson and V. Nygente. 2000. A noose trap for catching a
large arboreal lizard, Varanus olivaceus. Herpetological Review. 32(3):167-168.
Clements. T. 2003. Inventory of forest fragments in the Polillo Islands. In K.
Hampson et al. Wildlife and Conservation in the Polillo Islands. Final Report.
Multimedia CD (ISBN 1-904589-00-6) Viper Press, Glossop.
Galley, C. 2000. Preliminary Analysis of Forest in Sibulan Watershed reserve
and surrounding forest patches. In Bennett, Daniel [Ed.]. Wildlife of Polillo Island,
38
Philippines. University of Oxford - University of the Philippines at Los Banos
Polillo '99 project. Final report. Viper Press, Glossop. 2000: 1-174.
Gaulke, M. and E. Curio. 2001. A new monitor lizard from Panay Island,
Philippines. Spixiana 24 (3) 275-286.
Hampson, K. 2003. Amphibian distribution and abundance in the Polillo Islands.
In K. Hampson et al. Wildlife and Conservation in the Polillo Islands. Final
Report. Multimedia CD (ISBN 1-904589-00-6) Viper Press, Glossop.
Lehtinen, R. 2002. The use of screw pines(Pandanus spp.) by amphibians and
reptiles in Madagascar. Herpetological Bulletin 82, 20-25,
Reyes, M. A., D. Bennett and C. Oliveros. 2005. The monitor lizards of Camiguin
Island, Northern Philippines. Unpublished report, March 2005. 10pp.
Sweet, S. S. 1999. Spatial ecology of Varanus glauerti and V. glebopalma in
Northern Australia. Mertensiella 11:317-366.
Traeholt, C. 1994. The food and feeding behaviour of the water monitor Varanus
salvator in Malaysia. Malayan Nature Journal 47(3):331-343
Traeholt, C. 1995. A radio-telemetric study of the thermoregulation of free living
water monitor lizards (Varanus s. salvator). Comp. Biochem. Physiol. 165:125131.
39
Appendices
I - Notes on Sibalom Natural Park Survey, Antique, Panay. (Marisol
Pedregosa)
II - Investigation into the Population Status of Varanus olivaceus in Alabat
Island, Quezon Province. (Rogelio V. Sison)
III - Report on Study on the occurrence of fruit-eating monitor lizard in the
Northern Sierra Madre Natural Park. (Roldan Dugay)
40
Notes on Sibalom Natural Park Survey, Antique, Panay
(September-October 2005)
Marisol Pedregosa
Introduction
Sibalom Natural Park (SNP) is located in the southern portion of Antique with an
area of 5,511.47 hectares. It was established as a protected area on April 23,
2000. SNP has about 1,035 hectares of forest cover although the municipality of
Sibalom has about 800 hectares not covered by the boundaries of the protected
area. Habitat types such as old growth forest, lowland and mid-montane forests,
mixed secondary forests, grassland and reforestation areas can be found within
Sibalom Natural Park (SNP), province of Antique, Panay Island, Philippines.
Mabitang is recently described monitor lizard (Gaulke and Curio, 2001) is closely
related to Varanus olivaceus from Southern Luzon, Catanduanes and Polillo
islands. It has almost uniform black coloration, with slight indications of yellow on
neck, anterior part of dorsum, and dorsal sides of extremities. The head shape is
an elongate triangle from above with pointed and slightly domed snout, strongly
bulging nasal and temporal region. It has slit-like narial openings and positioned
closer to the tip of the snout than the eyes. The eyes are reddish brown, with
pink tongue and dark grey claws. It has finer scales and higher scale counts in
comparison to V. olivaceous, a triangular tail cross section, a well developed
41
double keeled scale row on its crest and a strongly keeled ventrals. According to
Gaulke and Curio 2001, the holotype of V.mabitang is exclusively vegetarian in
diet. It is essentially arboreal, and a secretive lowland forest species.
The main objective of this survey was to verify the presence of Varanus mabitang
in Sibalom Natural Park, Antique as previously claimed by the locals of Sibalom
The survey was done from September – to October 2005.
Note: During the survey, Tropical depression “Labuyo” hit the country, this
caused heavy rains and floods in the area
Ethno-biological interviews
? Varanus salvator nuchalis is locally known in Sibalom as “Halo” while
Varanus mabitang is locally known as “Abitang”
? Several hunters have claimed the presence of V.mabitang in the area. At
least 6 persons from different barangays (Brgy. Imparayan, Brgy.
Cabanbanan and Cabladan) have claimed that Abitang is present in their
area. These individuals have caught this species recently (1st week of July
and 2nd week of August 2005) for food and “pulutan”.
? Both species of Varanus were reported seen frequently when the sun
comes out after a consecutive 3 to 4 days of rain.
? Use of dogs in locating both Varanus species is still prevalent in the area.
This method used by the locals has been very advantageous to the hunter
as it makes the animal searching time very short.
? Some hunters interviewed claimed that this Abitang when escapes from
hunting dogs, would stay up in the tree or canopy for more than a week
until it feels safe and move in search for food again.
? Hunters also claimed that this species eats some fruits (see below for the
locally identified food plants) other than the known plants such as the
Pandanus , Canarium, etc.
? Abitang was also reported to feed on small crustacean in the river and
small streams within SNP.
Food Plants Locally Identified
1. BANAWAK – is a vine which was locally identified as food plant of the
Varanus mabitang
2. BIRIBID which has a long and oblong shaped fruit
3. BARASAN with rounded fruit, most likely of the Pandanus cf.
glauciferus species (needs to be verified)
4. BANGKAL is a tree which has a guava like fruit
5. TU-OG is a tree that bears black fruits, also eaten by bats and birds
6. TAPUYAY is a vine with round fruit like grapes, green when unripe and
maroon red when ripe
42
7. ALOPIDAN vine is the host vine of Rafflesia which is locally known as
“uroy”. It has green rounded fruits with dark brown spots when unripe,
yellow fruit when ripe.
Known Food Plant / Tree Genera search
Search for Pandanus species was also conducted in SNP. There are three
areas in SNP that have Pandanus species. One is in Lake Paco area, the
second one is located outside the forest area of Barangay Imparayan and the
third is located east of Ilihan with coordinates N 10.77178 E 122.11449 at 348
masl. Unfortunately, the Pandanus in Imparayan and Ilihan are not fruiting so it is
very hard to identify the species.
In Lake Paco area the Pandanus are located in the southern ridge of the lake.
Alopidan vines are also common in the area. The Pandanus species outside the
forest of Imparayan were planted by the locals to make mats and bags, the
Pandanus in Ilihan was later known to have also been planted for the same
purpose.
Locals also claimed that “pili” or Canarium species are also present in the area.
This has not been confirmed as no fruiting trees were available.
Varanus mabitang search
The search for V.mabitang was done in SNP. Areas locally reported where the
animal was frequently sighted such as rocky / limestone cliff-sides, trees and
basking areas were visited.
On several occasions, Varanus salvator nuchalis were observed basking on cliff
side rocks and trees. Other individuals were hand caught and released after
identification. Some individuals were only photograph from a distance.
One individual of about 2.5 -3 ft in total length was seen and photographed in the
‘Igang’ rocks (rocks and boulders on creeks) in Cansilayan I near Labangan
creek. The individual was not caught and was not identified to the species level
as it has immediately escaped to the rocks as soon as it heard our footsteps.
On the course of searching the Mabitang, Bulo (bamboo) traps were seen set in
locations were Varanus were frequently observed by the locals. This trap uses
dead Bufo marinus and usually catches Varanus salvator nuchalis.
Varanus track marks and claw marks were seen on river beds and several trees.
Some of these trees were observed for several hours from a considerable
distance to check if any individual Varanus will go back to the tree but none were
observed.
Some of the trees with claw marks have holes in the canopy level or on the
middle portion of the tree.
43
Search for fecal material
The feces of civet cats were found (see below), although local guides strongly
believed that some of those were the fecal material of Abitang. These scats
below were seen along the tracks found in the river bank of Mau-it River.
In summary, there is a strong local knowledge on the Giant Frugivorous Monitor
Lizard (GFML) in Sibalom, Antique. Although Pandanus and other known food
plants of GFML in Polillo are present in the area, local knowledge of other
species of food plants is very high. I believed that the GFML is present in
Sibalom has a different diet from that of Polillo so the search of fecal material
was not successful as I was looking for fecal material with Pandanus seeds.
These GFML are very secretive and elusive. The successful method of camera
or video trapping used in Polillo on GFML would help verifying its presence in
Sibalom.
List of the coordinates of some areas and important points:
Trail to SNP Peak
10.76830 N
122.12485 E 797 m a s l
10.77745 N
122.12388 E 485 m a s l
Rafflesia Viewing Deck
(near a tree with hole and
scratch marks)
Sitio Igmaru (way going to 10.78750 N
122.12276 E 276 m a s l
Lake Paco area)
Lake Paco Bunk House
10.77591 N
122.13544 E 596 m a s l
SNP Pine Area
10.77586 N
122.115 21 E 372 m a s l
Tapuyay tree with claw 10.78607 N
122.11481 E 242 m a s l
marks and bulo trap
SNP Watch Tower
10.77975 N
122.11204 E 346 m a s l
Ilihan point
10.77264 N
122.10970 E 369 m a s l
Rafflesia Site with claw 10.77426
122.13297 E 639 m a s l
marks near Lake Paco
Barangay Imparayan
10.78753 N
122.10532 E 220 m a s l
SNP Nursery
10.78404 N
122.10783 E 182 m a s l
ACKNOWLEDGEMENTS:
I would like to thank the following persons and institutions who helped me in
doing this study: Daniel Benett for giving me the chance to search for the
Mabitang in Sibalom, BP Conservation Programme, William Oliver, Pavel
Hospodarsky, Renee Lorica, DENR Region 7, Arlene Dalawis, Jun Manglinong,
Jesse Vego, Rene and Cecil Train and family, Sibalom Mayor Erick Lotilla,
Imparayan Brgy Caaptain Mary Paduganao, to the local community of Barangay
Imparayan, Tito and Merlyn Paduganao and family, Lumen Tiongco, to my
guides Rudy Sandoy, Tito Paduganao, Pedro Alintajan, Arnold Anting, Estong
a.k.a. Galman, Arnel Regino, Tony Regino and Arnel Alera and to the Bantay
Gubat of SNP.
44
Investigation into the Population Status of Varanus olivaceus in
Alabat Island, Quezon Province.
Rogelio V. Sison, Senior Curator, National Museum of the Philippines, Zoology
Division, Herpetology Section.
An investigation was conducted in August 2005 regarding the presence of the
population of Varanus olivaceus on the island of Alabat, Quezon Province. It was
confirmed by the Aeta natives that the animal still exists in the mountain forest of
Mount Camagong in barangat Bacong, Alabat Municipality. The vegetation of the
area consists of primary growth forest which is the typical habitat of V.olivaceus.
This is the only remaining fragment of forest on the entire island.
According to natives who trap them the refuges of this population are holes
amongst limestone walls. It is surrounded by rock boulders inside the forest
where they are well secured from intruders. As reporter by an Aeta trapper (Laki).
Their accessibility to their feeding areas could possibly be the reason why they
prefer this sight since it is within the vicinity of their feeding trees (locally called
Dau, Moling, mangga-mangga) which are allegedly abundant in the forest and
even forest outskirts.
Lately an individual of 60cm in length was sighted among these rock walls within
the boundary of Bgy. Villa Victoria and Bgy. Bacong within the forest 2km from
the latter, by the natives. Attempts were made to capture or see some individuals
but yielded negative results. They were instructed not to disturb the area to avoid
its dispersal, and to report any sightings or capture. Efforts were also made to
find some waste matter from these animals but yielded a negative result.
Last April 2005 an adult individual weighing an alleged 15kg was captured and
slaughtered by a group of Aeta natives enroute to Sito Tumiis and Sitio
Macalbang Villa Norte, Alabat Municipality. Skull and tail remnants were not
found. Local officials and natives were instructed to immediately report sightings
or capture in the future. If dead it should be preserved in 70% alcohol or 10%
formalin and immediately reported for retrieval. Also to encourage the natives
help in its population conservation.
In Perez Municipality no information was gathered regarding its present
distribution, because it has not been seen in the area for at least four years. It
seems that the only population is within 6the mountain range of Mount
Camacong in the vicinity of Bacong Watershed, Alabat Municipality.
Some other large lizards that are commonly known to the natives are Varanus
salvator and Hydrosaurus pustulosus. These are commonly caught usually in
second growth vegetation.
45
Further investigations might still yield more information on the faunal population
of the Island.
46
Report on the occurrence of fruit-eating monitor lizard in the Northern
Sierra Madre National Park
Roldan Dugay
In 2005, the Mampam Conservation received grant from the BP Conservation
Programme to allow local researchers trained for non-destructive research
method and verify the occurrence of Gray’s monitor and possibly new species of
fruit eating monitor lizard in the country. One of the projects received from fund
from it is the “Study on the occurrence of giant fruit eating monitor lizard in the
Northern Sierra Madre Natural Park”. Though it is known that the island of Luzon
harbors the species of this reptile, there has been no previous research and
study in some part of the main island to prove the evidence of the occurrence of
this animal. Northern Sierra Madre Natural Park is one of these areas hence the
Mampam Conservation in cooperation with the Cagayan Valley Programme on
Environment and Development initiated a project to scrutinize the occurrence of
fruit eating monitor within and outside the park.
The study focused in the Northern Sierra Madre Natural Park (NSMNP). The
NSMNP is so far the largest protected area in the country. It covers a total area
of more than 360,000 hectares of both marine and terrestrial ecosystems. The
park is located in the eastern portion of Isabela province encompassing nine
municipalities. It was proclaimed a protected area on 21 April 2003 through
Republic Act 9125. Prior to congressional action, part of the area had been
proclaimed as Palanan Wilderness Area in 1979 through Letter of Instruction
917-A due to its high diversity, ecosystem value and as a national heritage. The
park is one of the ten priority protected area created under the National
Integrated Protected Area System.
The study commences in June 2005 and the CVPED Office, EIC Building at the
Isabela State University served as a base of the project. In 2003, a Dutch
researcher, Merlijn van Weerd, took a photograph of a monitor lizard captured
and killed by a local hunter in Ambabok forest in Northern Sierra Madre Natural
Park. Prior to this, another picture of a live monitor lizard taken in 2001 in the
same area by a Filipino researcher. This species shows similarity to Varanus
olivaceus but has very unusual pattern and colouration thus require further study.
Working in a protected area like the NSMNP warrants prior permission from
various authorities.
Months of June covered the preparation of necessary papers and needed
documents for the application of working permit within and in the buffer zone of
the park. Frequent coordination with different agency stakeholders had also been
done until first part of the month of July. Papers and documents, which have
been geared up, include the formulation of project/research proposal as a
significant requirement for the issuance of Protected Area Management Board
47
(PAMB-NSMNP) and Gratuitous Permit. The NSMNP comprises nine (9)
municipalities compose of four (4) on the eastern/coastal side and five (5) on the
western slope. Of these municipalities, San Mariano, Mt. Ambabok and Mt.
Dialogo in particular, were initially identified as sightings for this species.
Concurrently, while preparing necessary documents, in the absence of a permit
from the Protected Area Management Board (PAMB) using the permit issued by
the Local Government Unit (LGU) of the municipality of San Mariano (dated 04
June 2005) interviews had been done as well on the months of June and July on
the upland communities of the NSMNP and on the lowland communities of this
municipality and its neighboring places for comparison. Hypothesis being tested
was there is only one species of monitor lizard in Northeast Luzon. Employing a
non-structured and semi structured questionnaire selected local residents,
hunters and Aetas (Indigenous people) were asked and tested regarding their
familiarity on monitor lizards. Results reveal that the locals on the lowland
communities are acquainted with one species of monitor lizard whereas people
near the buffer zone and within the park know two (2) species and can
distinguish each distinct characteristic. Bitatawa, Batikaw or Batikaw, as the local
residents distinguish, described further as a species of monitor lizard that feeds
mainly on fruits of forest trees.
Based on interviews, site validation in Dungsog and Dibanuangan Forests was
carried out where two of the local hunters mentioned that they have seen this
kind of lizard in this site. Dungsog is a second growth dipterocarp forest where
commercial logging took place in the area in the 70’s. Though Philippine law
stopped commercial logging in the early 90’s, illegal logging is still rampant in the
area during summer season. Enormous noises produce by a numerous number
of power saws might be the cause why there were no evidences on the presence
of this species of monitor lizard. The presence of Alas-as (Panadanus
luzonensis), young and old were observed in this forest but have no evidence of
the presence of monitor such as scratches and lizard faeces were found.
Pandanus abundance on hillsides is much higher than along streams and clumps
of plants were found growing uphill of any potential parent plant. Dracontomelon
dao (Dao) and Calamus ornatus (Limuran) were also noticed which is, according
to hunters, the monitor lizard is eating the fruits of these two plant species as
well. Comparing Dungsog to Dibanuangan has a little bit different. Some portion
of Dibanuangan is a limestone forest. I saw no disturbance in this site though my
field assistant told me this area was subjected before in illegal logging activities.
At present only the stumps of premium tree species were found and more or less
those trees were cut two years ago. There were approximately ten (10) fully
grown Pandanus with no fruits left were observed. Despite there were no
evidences found I believe that this area still harbors the species of fruit eating
monitor because the limestone is a very good retreat from an intruders. A
species of this fruit eating monitor lizard was accidentally caught by a hunter (one
of my interviewees) upstream of Dibanuangan forest. The hunter was asked to
surrender the lizard with a corresponding reward. Locals name the area where
the lizard was caught as Dibanti forest within Mt. Dialogo and is about one day
trekking from Dunoy, the take off point.
48
A permit to transport wildlife was obtained from the office of the Protected Area
Superintendent of the Northern Sierra Madre Natural Park as a requirement
before the lizard is brought in the National Museum of the Philippines in Manila
for donation. It is now being deposited in the said museum for further study.
On my interviews, there have been no hesitations regarding on answering
questions on the part of the hunters. I observed their sincerity, especially those
who have already caught a fruit eating monitor lizard that were not intentionally
for them to hunt this animal. Traps were set in the forest and are intended for wild
pig and deer. Local residents especially old men, claimed that previous decades
sightings of this reptile was just nearby and much higher populations when the
forest was still intact comparing now which are rare and seldom to see and are
now on very far forest areas. Their disappearance in those nearby forest areas
and possibly extinction is due mainly on habitat loss and not because of massive
hunting.
The Protected Area Management Board (PAMB) is the policy-making and
permitting body of the Northern Sierra Madre Natural Park (NSMNP). The
Regional Executive Director of the Department of Environment and Natural
Resources (DENR) as the chairman and the Local Chief Executives of the nine
(9) municipalities covered the NSMNP composed the board. One of the basic
requirements in order for obtaining a working permit within the park is the
presentation of a project proposal in either Executive Committee or EnBanc
meeting. In this case, the PAMB Executive Committee meeting was held on 02
August 2005 in Divilacan, Isabela one of the municipalities covered the NSMNP
and is located on the eastern/coastal side of the park. Accessibility of the area is
by means of plane and/or boat but the latter has no regular trip depending on
weather and sea condition. The project entitled “Study on the occurrence of fruit
eating monitor lizard in the Northern Sierra Madre Natural Park” was presented
on the said meeting. DENR officials such as the Regional Executive Director, the
Regional Technical Director and Division Chiefs for Protected Area Wildlife and
Coastal Zone Management Service, Manager of the Conservation InternationalSierra Madre Biodiversity Corridor Project and Municipal Mayors were present.
The proposed project was unanimously approved after few questions raised
subject to the compliance of the requirements as stipulated in the Department
Administrative Order 55 (DAO 55) series of 2004. Two days were spent in this
area to allocate time for some interviews with locals and Agta (Indigenous
People) hunters.
In the month of August to first week of September, to gain much expertise on a
non- destructive research method for Gray’s monitor lizard, a fieldwork on Polillo
Island was done. Assisting in lizard faeces mapping in different forest within the
project site was carried out. Checking of camera traps and lizard faeces
collection are also a main activity on the duration of a one-month fieldwork.
49
Activities in Sierra Madre resume after the fieldwork on Polillo Island in
September and October. The fieldwork took off on September 9 in San Mariano,
Mt. Dialogo as the target site. One night was spent in Dunoy as my entry point
and met Pedro Lorenzana, my field assistant and hunter caught the monitor
lizard, and Larry Pitpit served as a porter and camp guard. A temporary camp
was built, approximately one-hour hike to the site, made up of bamboo and sacktype roofing. Reconnaissance on nearby forest from the camp was carried out on
the following day in order to familiarize the area (this will serve as the permanent
camping site while camera trapping is on going on this site).
Assessment of Pandanus growth, fruiting trees and searches of lizard faeces
were done. Panadanus are on fruiting season and expected to be ripened in onemonth time however some of the Pandanus plants that were observed have no
fruit yet or otherwise have just finished its fruits. Of the area monitored, there was
only one Pili tree observed having ripe fruits near an open area but has no
scratches on trunk.
There were three lizard faeces having four or five Pandanus seeds in each pile
with a total of thirteen seeds have found on the other area. These were old
faeces of about a week ago or have just washed with rains. There are no
Pandanus trees neither fruiting or not nearby where the lizard faeces were found
other than an unidentified tree which has lot of scratches extending to a hole on
the upper portion of the trunk. In order to verify what is happening on this tree, a
camera trap will be set on the next field trip. Problem encountered was the
unfavorable weather condition. This situation halters the plan of setting camera
traps to an identified tree resources. As an alternate activity, interviews to
indigenous people community near the area were carried out. Indigenous
peoples are more acquainted with the characteristics of the monitor lizard. During
interviews, a public awareness campaign in collaboration with the Mabuwaya
Foundations staff was done in the upland communities. A part of these is the
contribution of articles in the CROC newsletter regarding the occurrence of giant
fruit eating Gray’s monitor lizard and its importance in the Northern Sierra Madre
Natural Park and adjacent areas.
After few days we decided to go back in the forest while weather got better. The
fieldwork in Sierra Madre took off on the 2nd day until 24th of October. Similar to
previous trip, a field assistant and a camp guard were hired from the Sitio of
Dunoy, which serve as my entry point, which are familiar of the Bitatawa (fruiteating monitor). Dungsog forest was explored thoroughly for this time. The
topography is moderately to strong terrain and in my assessment; Dungsog has
the potential as a refuge site for the monitor in the near future. Beside that this
site was totally disturbed during the summer season which large diameters of
premium tree species were no longer observed, Pandanus plants have seen in
ubiquitously within the area. Alas-as (Pandanus), locally known as Kadang in the
locality, has two (2) “classes”. Classes doesn’t relate to a variety or species but
on the sizes of these plants because most of these Pandanus that were
50
observed are young and yet they are now fruiting. Sizes are about standing One
(1) meter from the ground and have small stem diameters. With these sizes and
given the amount of Pandanus in this area, there was a difficulty in selecting and
identifying in which resource tree for setting a camera traps. Bigger Pandanus
plant shows no signs that the monitors are climbing it. Bidiw, commonly known
as kalagimay is also present in the area. I have a total count of five stems but
fruits were just finished. Fallen fruits were collected for comparison with the fruits
of Kalagimay in Polillo. I did not see any signs either that the lizards are feeding
on the fruit of Bidiw or Kalagimay for there were no scratches on trunks of this
plant.
Only one old lizard faeces was observed, three Pandanus seed in pile which is
starting to germinate. According to my field assistant this area was totally and
rampantly disturbed last summer of the previous year when the road was still
accessible by truck. In my opinion based on the old lizard faeces, the area was
then visiting by monitors before the summer season. According to my guide they
usually saw a lizard last year feeding on Pandanus fruit in the area. One of the
camera traps was set on a selected tree that has lot of scratches extending to a
hole on the trunk but it was decided to be removed because it was not safe to
leave the camera on that time.
A nest of a Bitatawa was reported by a farmer in a nearby village of San Isidro
(Interviews in this village had already done during the last fieldtrip). The said nest
is a hole in the ground and along a kaingin (slashed and burned) area planted
with corn. The opening of the hole has a diameter of about 40 centimeter and
located in a sloping area. With the characteristics of arboreal and shy, I was not
convinced that the lizard was a Bitatawa but the local confirmed it is a Bitatawa.
With his explanation about the pattern and coloration I was convinced it is a
Bitatawa. He explained further that the width of this lizard is about 30 centimeter.
I learned from my field assistant that this farmer was a hunter and one of his
companions before that is why he is so much familiar with the Bitatawa.
According to him, in the month of July they usually saw this lizard entering into
the hole and he tried once to set a trap on the opening but he was not successful
to catch it. Since then they did not already see and has no evidence anymore
that the animal is entering into the hole. Importance of the animal was explained
to him and told him the animal is already protected by law.
One of my colleagues, Edmund, likewise reported a sighting of this fruit eating
monitor lizard in the upland area of Cabagan (one of the municipalities covered
by the Northern Sierra Madre Natural Park). A farmer shuts a monitor lizard on
the top of a Taraw, Pinanga species. Edmund personally brought the tail of the
lizard and based on the yellow band/stripe I was encouraged to visit the area. I
talked with the farmer and he explained that he saw the lizard on the top of the
Taraw. According to him this kind of lizard is very rare and seldom for them to
see. The area is a secondary forest and there are no much Pandanus plants.
51
The area is being inhabited by the Ifugao people who are known for their slash
and burn activities within the forest zones.
After a two months fieldwork in Sierra Madre, I went back on Polillo Island in
November and December for two weeks each month fieldwork. Primarily conduct
transecting to assess current fruiting tree resources for the lizard. Continuation
for mapping of lizard faeces using a GPS was also carried out. Collection of
lizard faeces was also simultaneously done while checking of camera traps for all
the forest areas where activity of the lizard was identified. After a two weeks
fieldwork on Polillo Island, the Sierra Madre Project with its initial report was
presented in the en banc meeting of the Protected Area Management Board of
the Northern Sierra Madre Natural Park. Presentation of results in the PAMB is
one of the requirements agreed, before a project is approved, during the August
presentation of project proposal in the coast of the Sierra Madre. Final report will
be forwarded to the Office of the Protected Area Superintendent.
Since the lizard project in Sierra Madre started, local people in San Mariano
made aware of the importance of the animal as seed disperser and not as a food
item. Local people in lowland of the said municipality already know the existence
of two species of monitor lizard in Sierra Madre. Furthermore, presentation made
over local officials and responsible agency (DENR) through the Protected Area
Management Board educated and informed the occurrence of this species in the
park so an appropriate action will be taken up for the protection of the animal in
their area of responsibility.
In general, the overall accomplishment of the project is the dissemination of
information and the local stakeholders’ awareness on the importance and
occurrence of the giant fruit-eating Gray’s monitor lizard in Northeast Luzon.
However, necessary information should be generated for the on-site
conservation of this threatened species in Northeast Luzon. In total, there were
only 3 full months (July, September and October) fieldwork conducted in Sierra
Madre excluding month of June which is more on preparation.
Acknowledgements
I would like to thank Mampam conservation thru Daniel Bennett for funding and
providing technical support of the study in Sierra Madre. He made valuable
support to make the study possible. The DENR in general and the Protected
Area Management Board thru the Office Protected Area Superintendent in
particular for providing permit of the study. The CROC team headed by Merlijn
van Weerd and Jan van der Ploeg, CVPED Coordinator, for their assistance in
public awareness campaign, suggestions, advises and supervision. And lastly,
Dr. Andres Masipiquena, CVPED coordinators, for his support in obtaining
permits. To all of you, my sincere gratitude!
52
Annexes: Permits
53
54
55
PONCIANA C. GUING
56